This application claims benefit of Japanese Patent Application No. 11-374369 filed on Dec. 28, 1999, the contents of which are incorporated by the reference.
The present invention relates to duplexers and antenna apparatus using the same and, more particularly, to a antenna apparatus, which is constituted by an antenna part and a duplexer part and can be suitably used as portable telephone set or like mobile communication system for transmitting and receiving signals to and from a common antenna.
Recent rapid progress trend of introducing and dealing with computers and various data in our society is leading to pronounced spread of mobile communication, such as portable and vehicle-mounted telephone, systems. Also, as mobile communication antenna, various types have been proposed. As prior art antenna system examples, Japanese Patent Laid-Open No. 5-327319 discloses xe2x80x9cAntenna Duplexerxe2x80x9d, Japanese Patent Laid-Open No. 8-213835 discloses xe2x80x9cTwo-Frequency Common Antennaxe2x80x9d, and Japanese Patent Laid-Open No. 11-312907 discloses xe2x80x9cMatching Circuit Chip, Filter with Matching Circuit, Hybrid Antenna-duplexer System and Mobile Communication Systemxe2x80x9d.
A prior art antenna apparatus will now be described with reference to FIG. 3. The illustrated antenna apparatus comprises an antenna element or whip antenna 30, an antenna element connector part 31, an antenna element connector piece 32, a duplexer output part 33, a duplexer receiver input part 34, a duplexer transmitter input part 35, a duplexer 36, a radio part substrate 37, a high frequency matching capacitor 38 and a high frequency matching coil 39.
The relation between whip antenna and duplexer of a portable telephone set or the like is just like the relation between the whip antenna 30 and the duplexer 36. Specifically, the whip antenna 30 as antenna element is supported by a mold or like of the portable telephone set, and its high frequency electrode part 31 as its connector part is electrically coupled to the duplexer 36 by its connector piece 32, which is soldered to the radio part substrate 37. The connector piece 32 is connected to an antenna side terminal of the duplexer 36 by a high frequency strip or like provided on the substrate 37. The circuit of the duplexer 36 is formed by connecting the transmitter and receiver input parts (or terminals) 35 and 34 to a transmitter and a receiver part, respectively, of the substrate 37.
The duplexer 36 occupies a predetermined area on the radio part substrate 37 despite demands for its size and weight reduction. In addition, the whip antenna 30 has such a shape that a wasteful inner space is formed in the frame of the portable telephone set. Furthermore, since the duplexer 36 is mounted on the substrate 37, the whip antenna 30 and the duplexer 36, which are both 50 ohms in their characteristic impedance, are interconnected by a connector strip line or the like, and thus require the chip capacitor 38 and the chip coil 39 for their high frequency matching.
In still further aspect, as next era portable telephone system a W-CDMA system has been adopted. This communication system is a simultaneous transmission/reception system, and should always use a duplexer. The transmission/reception frequency band used in this system is 2 GHz and extremely high. Although the duplexer used has been considerably reduced, in view of its mounting in the portable telephone set the size reduction is insufficient to meet recently rapidly escalating demand for portable telephone set size reduction. That is, the insufficient size reduction of the duplexer that is herefore available is an undesired factor from the potable telephone size reduction standpoint.
An object of the present invention is to provide a duplexer and an antenna apparatus using the same, which can be reduced in size sufficiently to suit portable telephone sets now escalating in size reduction and nevertheless ensure various required electric properties.
According to an aspect of the present invention, there is provided a duplexer comprising a transmitter side dielectric filter having a semi-cylindrical shape, a receiver side dielectric filter having a semi-cylindrical shape, and a substrate interposed between axially sectional surfaces of the two dielectric filters facing each other, the two dielectric filters having output parts thereof connected to a connector, which is connected to an antenna.
The transmitter and receiver dielectric filters each have axial holes.
According to another aspect of the present invention, there is provided an antenna apparatus comprising an antenna part having an end part, in which the above duplexer is disposed.
According to other aspect of the present invention, there is provided an antenna apparatus comprising an antenna part having an end part defining an inner space, in which the above duplexer is disposed.
According to further aspect of the present invention, there is provided an antenna apparatus for transmitting and receiving transmission and reception signals by using a substantially rod-like antenna element, wherein: the antenna element has a hollow stem part; and a transmitter side filter and a receiver side filter both having a substantially semi-cylindrical shape are disposed in the stem part of the antenna element such as to constitute a duplexer.
According to still other aspect of the present invention, there is provided an antenna apparatus for transmitting and receiving transmission and reception signals by using a substantially rod-like antenna element, wherein: the antenna element has a hollow stem part; a transmitter side filter and a receiver side filter both having a substantially semi-cylindrical shape are disposed in the stem part of the antenna element such as to constitute a duplexer; and the substantially semi-cylindrical transmitter and receiver side filters are coupled together via a coupler substrate interposed therebetween.
The antenna element and the duplexer are interconnected by a connector provided on the coupler substrate. Input and output parts formed on outer surfaces of the transmitter and receiver side filters are connected by a plurality of connector pieces to a transmitter and a receiver part of a radio part of a portable telephone set or the like. The antenna element has a tip part greater in diameter than the remainder.
Other objects and features will be clarified from the following description with reference to attached drawings.